A word from Stephanie, the 'Cousin Itt' costume creator:

This is my two year old daughter dressed as Cousin Itt. With her squeaky voice that usually gets a lot of comments she was a perfect Cousin Itt. We also put some squeaky shoes on her to perfect the experience. You can't tell by the picture, of course, but she is playing with her hair and sucking her thumb. That is her most favorite thing in the world to do, so wearing a long synthetic wig under her yarn wig was her idea of heaven.